21396109 has 12 divisors (see below), whose sum is σ = 25810464. Its totient is φ = 17372232.

The previous prime is 21396103. The next prime is 21396119. The reversal of 21396109 is 90169312.

It is not a de Polignac number, because 21396109 - 2⁹ = 21395597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21396103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1707 + ... + 6760.

It is an arithmetic number, because the mean of its divisors is an integer number (2150872).

Almost surely, 2^21396109 is an apocalyptic number.

It is an amenable number.

21396109 is a deficient number, since it is larger than the sum of its proper divisors (4414355).

21396109 is an equidigital number, since it uses as much as digits as its factorization.

21396109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8512 (or 8493 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21396109 is about 4625.5928268710. The cubic root of 21396109 is about 277.6162821924.

The spelling of 21396109 in words is "twenty-one million, three hundred ninety-six thousand, one hundred nine".